Trailing blade coater with blade loading mechanism



Nov. 1, 1966 L. M. HILL ETAL 3,282,244

TRAILING BLADE COATER WITH BLADE LOADING MECHANISM Filed Sept. 6, 1962 6 SheetsSheet 1 IN V EN TORJ' $77204! Jsegaffnn if BY Z a; fer/Y/fi/Z Z4, w AT ?0RNEYs Nov. 1, 1966 L. M. HILL ETAL I 3,282,244

TRAILING BLADE COATER WITH BLADE LOADING MECHANISM Filed Sept. 6, 1962 6 Sheets-Sheet 5 I N V EN TORS flrrw/d .fasgalfafpzzli By 155 er/7.19;

/ A TTURNE YS Nov. 1, 1966 L. M. HILL ETAL 3,282,244

TRAILING BLADE COATER WITH BLADE LOADING MECHANISM Filed Sept. 6, 1962 6 Sheets-Sheet 4 I NVENTORS 14 M044 Jos iyfikzz A TTORNEYS L. M. HILL ETAL 3,282,244 TRAILING BLADE COATER WITH BLADE LOADING MECHANISM 6 Sheets-Sheet 5 Nov. 1, 1966 Filed Sept. 6, 1962 NOV- 1, 1966 L, L ETAL, 3,282,244

TRAILING BLADE COATER WITH BLADE LOADING MECHANISM Filed Sept. 6, 1962 6 Sheets-Sheet 6 we E K A T'1'( )RNIE YS United States Patent 3,282,244 TRAILING BLADE COATER WITH BLADE LOADING MECHANISM Lester M. Hill and Arnold Joseph Schmitt, Beloit, Wis.,

assignors to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Sept. 6, 1962, Ser. No. 221,813 13 Claims. (Cl. 118126) The present invention relates to improvements in coating mechanisms for paper Web coating machines and more particularly to a mechanism for loading a trailing blade coater at a controlled pressure and selectively changing the blade angle.

The invention is embodied in a trailing blade coating mechanism wherein coating is applied to the surface of a moving paper web carried on a coater backup roll and the coating is smoothed by a doctor blade held in smoothing close running relationship with the web. The flexible metal blade smooths the coating on the travelling web and is cantilever supported by a holder. It is desirable to be able to change the blade coating angle which is the angle between the blade and the tangent of the backing roll. The weight of coating applied varies with the hydrodynamic pressure, and increases as coating viscosity or speed increases. The blade angle will also vary the hydrodynamic pressure, and the smaller the angle between the tangent of the backing roll and the plane of the blade the greater the hydrodynamic pressure.

It is also desirable to accurately and controllably regulate the force applied to the blade holder to control the blade pressure. The blade pressure is the principal means by which the coating weight is controlled and the weight varies as a function of blade pressure. The trailing blade coater arrangement embodying the features of the present invention is primarily used where coating is applied to the travelling web ahead of the trailing blade although the features will be useful with a puddle coater wherein a pool of coating is held between the blade and the travelling web.

It is accordingly an object of the present invention to provide an improved trailing blade coater wherein the blade angle is readily and easily changed without requiring excessive time, and without adversely affecting the operation of other components of the mechanism.

Another object of the invention is the provision of an improved trailing blade coater wherein accurate control of the blade pressure is obtainable and wherein the blade pressure can be easily changed without adversely affecting sensitivity of control.

Another object of the invention is the provision of a trailing blade coater wherein a single mechanism may be employed for doctor blades of different resiliencies and wherein the blade pressure can be maintained accurately uniform or controllably varied.

Another object of the invention isthe provision of a trailing blade coater having an adjustable blade angle wherein the blade pressure is obtain-able by air pressure means which is capable of operating at higher or more easily controllable pressures for different ranges of blade pressures and different blade angles.

A further object of the invention is the provision of a coating machine with a trailing blade wherein the blade angle is quickly and easily changed and unwanted forces and stresses which tend to twist the blade or cause uneven blade pressures are eliminated.

A feature of the invention is the provision of a coating mechanism have a backup roll and a doctor blade supported in a holder with a pivotal support for the blade holder, and a shiftable mount for the pivotal support for 3 ,282,244 Patented Nov. 1, 1966 changing the angle of the blade with respect to the web, and provided with blade loading means connected to the blade holder for applying a blade loading force.

A further feature of the invention is the provision of a coating mechanism as set forth above wherein a fluid pressure operated blade loader applies a blade loading force to the blade holder and is radially shiftable to change the moment arm so that it may operate at optimum pressure for better control and sensitivity over different ranges of blade pressures.

Other objects, advantages and features will become more apparent with the teaching of the principles of the present invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings, in which FIGURE 1 is an end elevational view with parts broken away illustrating a trailing blade coating mechanism embodying principles of the present invention;

FIGURE 2 is a side elevational view of the mechanism of FIGURE 1 taken from the right side of FIGURE 1;

FIGURE 3 is a sectional view taken along line IIIIII of FIGURE 1;

FIGURE 4 is a detailed sectional view taken substantially along line IVIV of FIGURE 11;

FIGURE 5 is a schematic view illustrating the structural linkage relationship of the mechanism of FIGURES 1 through 3;

FIGURE 6 is a schematic view showing positions of the trailing blade;

FIGURE 7 is a schematic view showing different positions of the blade for different blade angle adjustments;

FIGURE 8 is a schematic view illustrating another form of adjustment mechanism for the trailing blade;

FIGURE 9 is a schematic view illustrating still another adjustment mechanism for the trailing blade;

FIGURE 10 is an end elevational view of another form of mechanism embodying the principles of the present invention; and

FIGURE 11 is an end elevational view illustrating still another form of the invention.

As shown on the drawings:

As illustrated in FIGURES 1 through 3 and 5, one end of the mechanism is shown that employs principles of the present invention, with the mechanism being substantially identical on both ends of the machine so that only one end may be described in detail. The mechanism embodies a backup roll 10 which rotates and carries on its surface travelling paper web W. For smoothing the coating on the web a trailing blade 11 is held in close running relation with the web, and coating is applied to the web surface ahead of the blade by a suitable means such as a coating applicator roll.

The coating blade 11 is clamped in a blade holder 12 which is pivotally mounted by being supported on an arm as will be described in further detail.

The blade holder 12 is supported by a mechanism which can be used to adjustably change the blade angle; which controllably applies a loading force to the blade holder to determine the blade pressure; and which is capable of dropping the blade down to a retracted position away from the roll or of moving the blade up to ready position adjacent the web on the roll 10.

FIGURE 5 shows this mechanism schematically and the schematic or diagrammatic illustration of arts is numbered corresponding to the .parts as they actually appear as shown in FIGURES 1 through 3.

The mechanism for supporting and controlling the doctor blade 11 includes a blade angle first arm 13. Pivotally mounted on the first arm 13 is a blade positioning and blade loading second arm 14.

Also pivotally mounted on the first arm 13, coaxial with the second arm 14, is a blade carrying third arm 15 on which is supported the blade holder 12.

The blade angle first arm 13 is made in the form of a bell crank, and has a lower arm 16 which is an-gularly adjustable to adjust the coating blade angle. The arm 16 is laterally adjusted as shown by the arrowed lines in FIGURE 5 to raise or lower the pivotal supports for the second arm 14 and third arm 15.

The blade 11 is moved by a blade positioning cylinder 17, which is connected to the second arm 14, between a ready position where it is just adjacent the web and a retracted position, as shown in the solid line position of FIGURE 6. This retracted position will be employed when the machine is being serviced, such as when a fresh web is being threaded over the backup roll or when the blade 11 is being changed and a fresh blade is being placed in the holder 12.

When the blade is in its ready position, a first blade loader 18, which is supported on the second arm 14, applies a first loading force to the third arm 15. This first loading force is suflicent to support the weight of the third arm 15, of the blade holder 12 and of the blade 11 and is capable of bringing the blade up into touch contact with the web W. While this first loader 18 primarily applies a supporting force rather than a blade loading force, for convenience of reference it is described as a blade loader, and its force is applied in parallel with and supplemental to a second blade loader 19. The second blade loader 19 is also supported on the second arm 14, and applies a variable loading force to the third arm 15 to control the blade loading force. The blade is then in operating position as shown in FIGURES 1 and 5, and in the dotted line position of FIGURE6.

As illustrated in FIGURE 5, the first blade loader 18 is in the form of an air spring which is a closed flexible container of the type which will be appreciated by those versed in the art, having a predetermined force deflection characteristic and operated by the fluid pressure within. Air pressure is directed to the air spring 18 through a line 18a at substantially constant pressure to obtain the support force needed.

Air pressure is supplied to the second loader 19 which is also in the form of an air spring, through a supply line 190 controlled by a variable valve 191). Change in the setting of the valve 1% will vary the air pressure within the air spring 19 to vary the force.

The air spring 19 is adjustable radially with respect to supporting arm 14 so as to change the effective moment arm between the two arms 14 and 15. This permits using a relatively uniform range of supply pressure from the valve 19b for better control. If a light blade pressure is to be employed, it would normally be necssary to substantially reduce the pres-sure within the air spring 19 thereby falling down into a low pressure range where control is diflicult. However, with the instant arrangement, the air spring 19 can be shifted inwardly to decrease the moment arm (and thereby decrease the force on the blade 11), and therefore the air spring can continue to operate at a higher pressure even with low blade loading pressures and more accurate loading control can be obtained. This makes it possible to use the arrangement for blades and holders of different weights without changing the design of the loaders 18 and 19 and the associated mechanism.

As to structural details of the mechanism, the blade supporting and angle adjusting mechanism is supported on a stand 20 which is part of the coating machine. At the top of the stand is a pin 21 which supports a bearing 22 that provides pivotal support for the first arm 13.

The pin 21 extends beyond the inner edge of the stand, as shown in FIGURES 2 and 3, and provides a stop for the second arm 14. The second arm has a seat 23 which engages the fixed stop pin 21 to positively fix the operating position of the second arm 14 when it is elevate-d into operating position by the cylinder 17.

The first arm 13 carries a boss 30 which provides a journal for supporting a bearing 31 for the second arm 14.

On the third anm 15 is a vertical plate 32 against which the first loader air spring 18 acts. The third arm 15 also has a horizontal plate 33 against which the second loader air spring 19 acts. An adjustable stop .pin 34 is mounted on the second arm 14 to be engaged by the plate 33 when the loader air spring 19 is collapsed to prevent damage to the air spring.

The air spring 19 is provided with a suitable adjustment mechanism 19a for selectively adjusting its radial posi tion, as above described, in the directions indicated by arrowed lines 19a. For example the second arm 14 and 1 the third arm 15 may have radial slides with the air spring 19 having releasable clamps to clamp it in a selected radial position.

The arm 15 is pivotally supported on a :pin 35 carried in a bearing 36 on the first arm 13, coaxial with the second arm 14.

For adjusting the position of the blade angle, the arm 16 has an internally threaded lower boss 24 which receives the threaded tube 25. By rotation of the tube, the position of the arm 16 will be changed. Threaded into the tube 25 at each end are bolts 26 and 27 and their heads engage stop surfaces 28 and 29 on the stand 20. The bolts are provided with lock nuts, and for adjustment of the blade angle, the bolts are turned inwardly so that the tube 25 can be rotated to move the arm 16 in either direction. The adjustment of the arm 16 will raise or lower the first arm 13 to change the position of the blade 11 between its minimum angle, where it contacts the backup roll at the line 30 (position P to its maximum angle where it contacts the roll at the line 31 (position P as shown by the bnoken line blade 11'. Lines 30 and 31 indicate the locations of minimum and maximum blade angle and are drawn from the axial center of the roll 10, FIGURES 1 and 7. The bisector of the angle between the lines 30 and 31 is indicated by the line 32, and the pivotal support pin 21 for the first arm 13 is located on this bisector.

The support pin 21 for the first arm 13 is located on the intersection of the bisector 32 of lines 30 and 31 and the line drawn perpendicular to the line 35 connecting the upper and lower positions P and P of support pin 35 and going through a point on said connecting line 35' lying half way between said upper and lower position.

The location of pivot point 21 is very critical and should be made as described above. The upper and lower position of the support pin 35, is, of course, .a function of the maximum adjustment of threaded box 24 and may thus be determined. It should also be noted that in order to suit particular design conditions an arbitrary line may be used in order to locate the position of pivot pin 21. The coating blade 11, however, may still be used between the lines 30 and 31 (positions P and P only.

For dropping the coating blade 11 downwardly to retracted position, as shown in the solid line position of FIGURE 6, or moving it up to operating position, as shown in FIGURES l and 5 and the dotted line position of FIGURE 6, the cylinder 17 has a piston therein with a piston rod 38 pivotally connected to the arm 14. The cylinder is pivotally supported on a bracket 39 on the stand 20. The piston within the cylinder 17 need not have a fixed stop inasmuch as the pivot pin 21 will locate the operative position of the second arm 14.

After the cylinder 17 moves the blade to ready position, air springs 18 and 19 are pressured to hold the blade in close running position against the web.

FIGURE 8 illustrates a modified adjustment arrangement for changing the blade angle. A backup roll 40 carries a paper web W and a flexible trailing coating blade 41 by a mechanism not shown. The blade is supported in a holder 42 which is pivoted on a support 43 which slides along a horizontally extending support 44 and can be adjustably fixed thereon and is movable from the solid line position to the dotted line position of FIG- URE 8 for changing the blade angle.

In FIGURE 9, another arrangement is illustrated with a backup roll 45 supporting a travelling paper web W. A trailing coating blade 46 is supported in a holder 47 mounted on a pivotal support 48. The pivotal support is adjustable in position along a vertical slide 49 to change the blade angle from the solid line position to the dotted line position shown in FIGURE 9. Suitable blade loading mechanism and blade positioning mechanism is provided, which may be similar to that shown in the other figures of the drawings, and need not be shown in detail.

FIGURE illustrates a backup roll 50 with a web W carried on the surface thereof. A trailing coating blade 53 is in close running relation to the web for smoothing coating applied to the surface thereof by coating applicator roll 51. The applicator roll runs in a pool of coating carried in a pan 52 beneath the roll 51. The coating blade 53 is supported in a blade holder 54.

For supporting and positioning the coating blade 53, a first arm 55 is mounted on a stand 56 and is pivoted thereon at 57.

The position of the first arm 55 is varied to change the blade angle by a blade angle position adjustment mechanism 58. The mechanism 58 includes a differentially threaded screw 59 which is internally threaded into a hollow screw 60 at one end and a hollow screw 62a at the other end so that rotation of the screw 59 in one direction will raise the arm 55 and in the other direction will lower the arm 55. The screw 59 has threading at different pitch at opposite ends and this arrangement provides for very small finite adjustments of the angle of the blade 53, and the adjusted angle is locked by clamps 61 and 62 which lock the adjustment mechanism in adjusted position. As will be appreciated various selectively accurate controllable adjustment mechanisms may be employed to adjust the position of the first arm 55 Pivotally mounted on the first arm is a second arm 64 which is pivoted on the first arm at 63. The second arm 64 is pivoted on the first arm by the operation of a piston rod 65 which is connected at its upper end to the first arm 64-. The piston rod is connected to a piston Within a cylindder 66 which is pivotally mounted at 69 on a pivotal arm 68. The arm 68 is pivotally mounted at 78 on the stand 67. The piston within the cylinder 66 has a fixed stop therein and moves the blade 53 between a retracted position away from the web W and an operating position in close adjacency to the web W.

The blade loading force is applied by a closed air spring 71 mounted on the stand 67 and acting on the arm 68. An air spring 71a is used to bring the blade 53 into contact with the web W at zero blade pressure. A pressure supply line is connected to the air springs 71 and 7111. Air spring 71 is adjustable in position relative to the pivot point 70 by mechanism indicated schematically by the arrowed lines 71' to afford a larger range of blade pressures under ideal air pressure conditions (the reasons for this adjustment are the same as for the air spring 19 of FIGURE 1).

FIGURE 11 shows another arrangement wherein a backup roll 72 supports a travelling paper web W. A trailing coating blade 73 is in close running relation with the web W, and is carried in a blade holder 74.

For loading the blade, for adjusting its angle, and for moving it between operating position and a retracted position, a first arm 75 is pivotally mounted at 76 on a stand 77. The pivotal position of the first arm 75 determines the blade angle, and this is regulated by an adjustment mechanism 78, FIGURES 4 and 11. The adjustment mechanism includes a screw 83 which has different pitch threads at its opposite ends, and one end is threaded into a sleeve 79 which is held in a support 82 by collars 80 and 81 threaded on the sleeve. The other end of the screw 83 is threaded into an upper clamping fitting 84 connected to the arm 75.

The blade holder 74 is carried on a second arm 85 pivotally mounted at 86 on the first arm 75. The second arm 85 is pivoted on the first arm by a piston rod 87 on a piston slidably mounted within a cylinder 88 which has internal stops to fix the extended position of the rod 87. The cylinder 88 is carried on an arm 90 pivotally mounted at 89 on the stand 77. The piston within the cylinder 88 is extended by admitting fluid pressure to the cylinder to move the blade up into operating position, and the pressure within the cylinder is relieved to drop the blade down to a retracted position. It should be noted that the pivot point of rod end 87 and of arm 75 at 76 are in the same elevational location. This is necessary because point 76 must remain the same position when the blade angle is changed by adjustment mechanism 78 is order to maintain the same cylinder stroke.

For applying a loading pressure to the blade, flexible walled closed chamber air springs 91 and 92 are positioned between the stand 77 and the arm 90. One of the air springs is arranged to apply a constant loading pressure to support the weight of the arm 90, the cylinder 88, and of the arm 85 with the holder 74, and the other air spring applies a variable controlled pressure to regulate the blade loading force. Air pressure is supplied to the air springs 91 and 92 from a suitable source controlled by valves. A stop 93 engages a surface 94 to limit the pivotal movement of the arm 90 and prevent damage to the springs 91 and 92 when they are collapsed.

The arrangement of FIGURES 3-7, 10 and 11 are preferred over those shown in FIGURES 8 and 9 and the embodiments of FIGURES 1 and 11 in particular are capable of easy alignment and have additional advantages. The arrangement of FIGURE 1 also has fewer pivot points than the arrangement of FIGURE 11.

Thus it will be seen that we have provided an improved coating mechanism which meets the objectives and advantages above set forth and which accomplishes an improved blade adjustment, blade loading, and blade positioning.

The drawings and specification present a detailed disclosure of the preferred embodiments of the invention, and it is to be understood that the invention is not limited to the specific forms disclosed, but covers all modifications, changes and alternative constructions falling within the scope of the claims.

We claim as our invention:

1. In a coating mechanism for a paper web coating machine, the combination comprising,

a backup roll for supporting a travelling web,

a doctor blade supported in a blade holder for smoothing coating on the web,

a pivotally mounted blade angle determining first arm,

a blade positioning and loading second arm pivotally mounted on said first arm,

a blade carrying third arm pivotally mounted on said first arm coaxial with the pivotal mounting of the second arm and supporting the blade holder,

blade positioning means for moving said pivotally mounted second arm between a retracted position and an operating position,

first blade loading means connected between said second and third arms for applying a blade loading force to the third arm sufficient to support the weight of the third arm and blade holder,

and second blade loading means connected between said second and third arms for applying a blade loading force to said third arm.

2. In a coating mechanism -for a paper Web coating machine, the combination comprising,

a backup roll for supporting a travelling web,

a doctor blade supported in a blade holder for smoothing coating on the web,

a pivotally mounted blade angle determining first arm,

a blade positioning and loading second arm pivotally mounted on said first arm,

a blade carrying third arm pivotally mounted on said first arm coaxial with the pivotal mounting of the second arm and supporting the blade holder,

blade positioning means for moving said pivotally mounted second arm between a retracted position and an operating position,

first blade loading means connected between said second and third arms for applying a blade loading force to the third arm suflicient to support the weight of the third arm and blade holder,

second blade loading means connected between said second and third arms for applying a blade loading force to said third arm,

and means for shifting the radial position of said second blade loading means relative to the pivotal connection between said second and third arms.

3. In a coating mechanism for a paper coating machine, the combination comprising,

a backup roll for supporting a travelling paper web,

a doctor blade holder for a doctor blade for smoothing coating on the supported paper web,

a pivotal support for said blade holder,

a shiftable mount for said pivotal support for changing the angle of the blade with respect to the Web,

and blade loading means connected to the blade holder for applying a blade loading force.

4. In a coating mechanism for a paper coating machine, the combination comprising,

a backup roll for supporting a travelling paper web,

a doctor blade holder for a doctor blade for smoothing coating on the supported paper web,

a pivotal support for said blade holder,

a shiftable mount for said pivotal support for changing the angle of the blade with respect to the web,

means for adjustably fixing the position of said mount over a range of positions varying from maximum blade angle to minimum blade angle,

and blade loading means connected to the blade holder for applying a blade loading force.

5. In a coating mechanism for a paper coating machine, the combination comprising,

a backup roll for supporting a travelling paper web,

a doctor blade holder for a doctor blade for smoothing coating on the supported paper web,

a pivot support for said blade holder,

at shiftable mount for said pivotal support for changing the angle of the blade with respect to the web,

a blade positioner connected to the blade holder pivoting it on the support between a retracted position away from the web and an operating position,

and an inflatable resilient bellows blade loader connected to the blade holder for controllably urging it toward the backup roll to load the blade.

6. In a coating mechanism for a paper coating machine, the combination comprising,

:a backup roll for supporting a travelling paper web,

a doctor blade holder for a doctor blade for smoothing coating on the supported paper web,

a pivotal support for said blade holder,

a shiftable mount supported on a pivot point for said pivotal support and shiftable about said pivot point for changing the angle of the blade with respect to the web,

a first resilient inflatable bellows loader connected to the blade holder for urging it toward the backup roll,

and a second inflatable resilient bellows loader connected to the blade holder and being controllably variable so that the second loader will vary the blade pressure maintaining it in close running relationship to the web.

7. In a coating mechanism for a paper coating machine, the combination comprising,

a backup roll for supporting a travelling paper web,

a doctor blade holder for a doctor blade for smoothing coating on the supported paper web,

a pivotal support for said blade holder,

a shiftable mount for said pivotal support for changing the angle of the blade with respect to the web,

a resilient inflatable bellows blade loader connected to said holder for applying a blade loading force,

and means for selectively shifting the radial position of the loader relative to the axis of said support to change the effective moment arm and the effective force applied to the blade.

8. In a coating mechanism for a paper coating machine, the combination comprising,

a backup roll for supporting a travelling paper web,

a doctor blade holder for a doctor blade for smoothing coating on the supported paper web,

a pivotal support for said blade holder,

a shiftable mount for said pivotal support for changing the angle of the blade with respect to the web,

a first loader connected to the blade holder and applying a force sufiicient to support the weight of the blade and holder,

a second loader connected to the blade holder and applying a force for controlling the blade loading pressure,

and means for selectively shifting the radial position of the second loader relative to said support to change the effective moment arm and the effective force applied to the blade.

9. In a coating mechanism for a paper coating machine, the combination comprising,

a backup roll for supporting a travelling paper web,

a doctor blade holder for a doctor blade for smoothing coating on the supported paper web,

a pivotal support for said blade holder,

a shiftable mount for said pivotal support for changing the angle of the blade with respect to the web,

a first loader connected to the blade holder and applying a force sufficient to support the weight of the blade and holder,

a second loader connected to the blade holder and applying a force for controlling the blade loading pressure,

means for selectively shifting the radial position of the second loader relative to said support to change the effective moment arm and the effective force applied to the blade,

and a positioner connected to said first and second loaders and movable to move the loaders and blade between a retracted, position with the blade away from the roll and an operating position.

10. In a coating mechanism for a paper coating machine, the combination comprising,

a backup roll for supporting a travelling paper web,

a doctor blade holder for a doctor blade for smoothing coating on the supported paper web,

a pivotal support for said blade holder,

a shiftable mount for said pivotal support for changing the angle of the blade with respect to the web,

a loader connected to the blade holder for loading the blade against the web,

an arm supporting the loader,

a positioner connected to the loader arm for moving the loader and the blade between a retracted position with the blade away from the roll and in an operating position,

9 l and a fixed stop limiting movement of said arm at said a backup roll for supporting a travelling paper Web,

operating position for establishing a fixed operating a doctor blade holder for a doctor blade for smoothing position for the loader. coating on the supported paper web, 11. In a coating mechanism for a paper coating maa first pivotal support arm, chine, the combination comprising, a second pivotal support arm pivotally mounted. on the a backup roll for supporting a travelling paper web, first arm and supporting the blade holder, a doctor blade holder for a doctor blade for smoothing means for adjusting the pivotal position of the first coating on the supported paper web, arm to change the blade angle, a pivotal support for said blade holder, and a pivotal support for the first arm located on the a pivotal arm carrying said pivotal support for changbisector of an angle formed between radial lines ing the position thereof to change the blade angle, extending from the center of the backup roll through and means for adjusting the angular position of the the points of contact of the doctor blade with the pivotal arm to change the blade angle. roll at maximum and minimum blade angles. 12. In a coating mechanism for a paper coating machine, the combination comprising, References Cited y the Examine! a backup roll for supporting a travelling paper web, UNITED STATES PATENTS a igifg jg gg 2 3 258333222 ig; forsmoothmg 3,030,917 4/1962 Brown et al. 118-413 3,113,890 12/1963 Johnson 118126 a pivot-a1 support for said blade holder,

a pivotal arm carrying said pivotal support for changg gg 118*126 ing the position thereof to change the blade angle, 3176651 4/1965 fi s and a differential threaded compound screw connected p to the pivotal arm and rotatable to change the pivotal CHARLES WILLMUTH Primary Examiner position of the pivotal arm to change the blade angle.

13. In a coating mechanism for a paper coating ma- MORRIS KAPLAN Exammer' chine, the combination comprising, L. G. MACHLIN, Assistant Examiner. 

1. IN A COATING MECHANISM FOR A PAPER WEB COATING MACHINE, THE COMBINATION COMPRISING, A BACKUP ROLL FOR SUPPORTING A TRAVELLING WEB, A DOCTOR BLADE SUPPORTED IN A BLADE HOLDER FOR SMOOTHING COATING ON THE WEB, A PIVOTALLY MOUNTED BLADE ANGLE DETERMINING FIRST ARM, A BLADE POSITIONING AND LOADING SECOND ARM PIVOTALLY MOUNTED ON SAID FIRST ARM, A BLADE CARRYING THIRD ARM PIVOTALLY MOUNTED ON SAID FIRST ARM COAXIAL WITH THE PIVOTAL MOUNTING OF THE SECOND ARM AND SUPPORTING THE BLADE HOLDER, BLADE POSITIONING MEANS FOR MOVING SAID PIVOTALLY MOUNTED SECOND ARM BETWEEN A RETRACTED POSITION AND AN OPERATING POSITION, FIRST BLADE LOADING MEANS CONNECTED BETWEEN SAID SECOND AND THIRD ARMS FOR APPLYING A BLADE LOADING FORCE TO THE THIRD ARM SUFFICIENT TO SUPPORT THE WEIGHT OF THE THIRD ARM AND BLADE HOLDER, 